//https://api.dartlang.org/stable/2.2.0/dart-io/HttpHeaders-class.html
//设置或获取请求头
import 'dart:io';
main() {
  HttpClient httpClient =HttpClient();
  
  //设置请求头request.headers.set(HttpHeaders.cacheControlHeader,'max-age=3600, must-revalidate');

  //读取请求头print(request.headers.value(HttpHeaders.userAgentHeader));


  //******常量****
  //acceptCharsetHeader→ constString  -- "accept-charset"

  //acceptEncodingHeader→ constString -- "accept-encoding"

  //acceptLanguageHeader→ constString -- "accept-language"

  //acceptRangesHeader→ constString -- "accept-ranges"

  //ageHeader→ constString --"age"

  //allowHeader→ constString  --"allow"

  //authorizationHeader→ constString --"authorization"

  //cacheControlHeader→ constString --"cache-control"

  //connectionHeader→ constString --"connection"

  //contentEncodingHeader→ constString --"content-encoding"

  //contentLanguageHeader→ constString --"content-language"

  //contentLengthHeader→ constString --"content-length"

  //contentLocationHeader→ constString --"content-location"
 
  //contentMD5Header→ constString --"content-md5"

  //contentRangeHeader→ constString --"content-range"

  //contentTypeHeader→ constString --"content-type"

  //cookieHeader→ constString --"cookie"

  //dateHeader→ constString --"date"

  //entityHeaders→ constList<String>
  //const [allowHeader, contentEncodingHeader, contentLanguageHeader, contentLengthHeader, contentLocationHeader, contentMD5Header, contentRangeHeader, contentTypeHeader, expiresHeader, lastModifiedHeader…

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}